Coal Age

APR 2018

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20 April 2018 communications New Wireless Tech for Underground Mines Could Save Lives, Costs Innovations promise to boost signals, detect gases anywhere, and provide continuous tracking without cables or junction boxes by jesse morton, technical writer South Africa's primary miner union re- cently presented a list of concerns to the government that speak to the startling increase in miner fatalities there. The list mostly focused on issues related to worker fatigue but closed with an emphasis on the need for improved modes of communica- tion. That need is both timeless and uni- versal among miners around the world, especially underground miners. In re- sponse to that need, in the last two years, emergent underground communications technologies hit the market promising to solve some historically formidable chal- lenges. A quick review of those technolo- gies reveals both the viable options now available and the general direction of the evolution of such technologies. Wireless Extension Solution In second-quarter 2017, Innovative Wireless Technologies (IWT) released its last-mile safety system connec- tivity solution, HDRMesh, billed as a wireless extension or booster solu- tion for a fiber optic network. "IWT products embedding HDRMesh tech- nology provide long-range, reliable com- munications in hard-to-reach working areas, even around corners, with no fiber interconnect between them," said Phil Carrier, vice president, sales and market- ing, IWT. "It is currently planned to be used as fiber replacement in a tunnel con- struction project." HDRMesh leverages the company's established flagship underground wire- less communications system. SENTI- NEL, which is comprised of line- or bat- tery-powered networked mesh nodes, dates back to 2006 and the Miner Act, "which required underground coal mines to install post-incident two-way commu- nications and tracking systems," Carrier said. "The first system was developed from mid-2007 through December 2008, with continued product development to this day." With MSHA approval, deployments began in 2009. SENTINEL supports voice, text, track- ing, data, personnel and vehicle tracking tags, two voice handset models, dispatch and tracking stations, and services for technical support and maintenance, IWT reported. The "same system is software upgradeable to add voice, using the same network." The company defined wireless as no requisite line power or fiber inter- connect. "In the working sections, the battery mesh nodes provide the required communications coverage, while small, battery-operated, wireless beacons pro- vide continuous 200-ft tracking." In cer- tain applications, the batteries are good for a year. The system was designed to enable two-way voice communications after the worst happens. "We strongly believe that voice communication is the only realistic communications means in a smoke-filled, post-accident environment," IWT said. It does this without cabling, distinguishing it from the competition, Carrier said. "There are other systems that support voice, or don't require cabling, but none other than the SENTINEL system that provides voice without cabling," he said. Leaky feeder or WIFI systems require cabling between infrastructure devices, he said. "Other systems don't require cabling but do not support voice communications, only tex- ting," Carrier said. "Still other systems only support communications or tracking." Another crucial benefit of SENTINEL is that it enables continuous tracking, he said. "RFID tracking systems only provide zonal tracking," at best revealing "you were here," he said. The IWT system pro- vides "you are here" data. The system is pitched as easy to install, reliable and versatile. It is also field-prov- en. "We have replaced every other type of system, while the IWT system has never been replaced by a competing system," Carrier said. SENTINEL improves produc- tivity, data shows, he said. "This is due to the value of continuous communications and tracking," Carrier said. "These im- provements can add up to millions of dol- Above, IWT's dispatch tracking screen, mTracker. (Photo: IWT)

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